OB: moles class #3Moles with gases,

moles → mass problems and

moles → particles problems.

Reference tables and calculators now. Lots of paper please.

Get ready to draw a shark

The mole in chemistry has many connections.

One mole = 6.02 x 1023 particles (atoms, molecules, FU’s, etc.)

One mole = the molar mass of an element

One mole = the molar mass of a compound

Now…

One mole of any gas = 22.4 liters of gas*

*the gas must be at what’s called standard temperature + pressure which is on table A.

That’s 273 Kelvin or 0°C and one atmosphere pressure (normal)

AKA: STP

Moles connect mass to volume to numbers of particles. It’s like a universal math tool that you can use to make amazing connections.

On the next page you will draw a cool map, please use at least one half a page and be neat. Copy everything especially the shark…

Mole Island

Chemistry Vacationland

MoleIsland

Volume Island

Particle Island

MassIsland

1 mole = 22.4 L of gas

1 mole = 6.02 x 1023 particles 1 mole = molar mass

Stay on the islands or use the bridges only.

Pay the toll in both directions.

If you try to take a shortcut, the Mole Shark will eat you.

The biggest mole problem is only 2 steps.

Always use units.

Problem #1 today

How many liters of helium gas are in 65.3 gof helium?

(hint: start at the beginning)

MoleIsland

Volume Island

Particle Island

MassIsland

65.3 g He

1 mole = 22.4 L of gas

1 mole = 6.02 x 1023 particles 1 mole = molar mass

STEP ONE

STEP TWO

Figure out where you are starting, and where you want to go, stay on the bridges!

No Shark Problems.

65.3 g He1

How many liters of helium gas are in 65.3 grams of helium?

How many liters of helium gas are in 65.3 grams of helium?Using the map, start at mass island, go to mole island, then go on to volume island.

65.3 g He1

1 mole He4 g He

x = 16.3 moles He

16.3 moles He1 x

22.4 L He1 mole He

= 365 liters He

This is a 2 step problem, watch SF, go slow, use your units always.

Problem #2, if you find exactly3.58 x 1024 atoms of aluminum, how many grams do you have?This is another 2 step problem, starting at particle island, to moles, then a trip to mass island.

Problem #2, if you find exactly3.58 x 1024 atoms of aluminum, how many grams do you have?

3.58 x 1024 atoms Al1

x1 mole Al

6.02 x 1023 atoms Al=

3.586.02

x 1024

1023= 0.595 x 101 moles Al 5.95 moles Al

one more step!

5.95 moles Al1

x 27 g Al1 mole Al

= 161 g Al (3 SF)

The mole island map will be your handy guide through all mole problems. No problems exist that can’t be figured out with the map. Always use units, always write big enough to cancel out, always go slowly, and you cannot go wrong.

Last problem for now: you are re-gifted a present from your weird Uncle Al. He gives you a canister that says it contains exactly 7.99 x 1022 molecules of nitrogen gas. What does this gas weigh? (remember HONClBrIF twins!)

7.99 x 1022 molecules N2

1

X

7.99 x 1022 molecules N2

1

x1 mole N2

6.02 x 1023 molecules N2

=

7.996.02

x 1022

1023 = 1.33 x 10-1 moles N2

1.33 x 10-1 moles N2 = 0.133 moles N2

0.133 moles N2

1x

28 g N2

1 mole N2

= 3.72 g N2 gas

Next, we’ll do the Mole Lab.

Come on time, come with a calculator and a smile.

Homework tonight… start reading the Mole BASICS.

Peace, love and chemistry.